Thermal Dart Article & Plans
August 1970 American Aircraft Modeler Article
The AMA's Delta Dart program has been around a long time, and is still its primary tool for introducing young kids to the model aviation hobby. The Delta Dart's easily and quickly built, strong, forgiving frame and simple dry tissue covering makes for almost guaranteed success with all newcomers... and they're cheap to boot. This Thermal Dart is a step up really only in size with not not too much added complexity. Its 24" wingspan, versus the Delta Dart's 12" wingspan, provides for longer flights and make it easier to see. Frank Ehling designed both the original Delta Dart and the Thermal Dart.|
Thermal DartFrank Ehling
Although this model is easy to construct, building a Delta Dart or AMA Cub first will aid in making a better Thermal Dart. It uses a larger propeller and a stronger rubber motor than the Delta Dart, thus enabling it to climb higher, and has a larger wing, which allows it to glide longer. By gluing the wing to the wing saddle, the wing can slide along the motor stick, making it possible to adjust the model to obtain good glides without stalling after the rubber is unwound. A little practice flying will indicate the best wing location for a smooth glide.
Built a Delta Dart? Now try this higher-performance version, easier to make and adjust.
Size of Thermal Dart permits experimenting with wood sizes to improve performance, but keep same areas and dimensions.
In case you wonder, checkerboard pattern tissue should be available at leading hobby shops. Prop sanded to thin and lighten.
Both photos, Frank Pierce
Begin construction by laying Saran Wrap over the entire full-size plan; over this place the tissue covering. Hold both layers in place with small pieces of Scotch Tape at the corners. Start on the wing by cutting the leading and trailing edges from 3/32 x 1/4". Cement them to the tissue and then add the ribs, using as little glue as possible. To make the wing saddle, cement a piece of 1/8" sq. directly below the dihedral joint (the two center ribs) when putting the dihedral in the wing. When this has dried, the side of the saddle can be cut from 1/16" sheet and cemented to the 1/8" sq. as shown on the front view of the wing.
The stabilizer (tail) is constructed like the wing. However, note that the stabilizer and rudder are made out of 1/16 x 1/8". It is important to keep the tail end of this model light. When building the rudder, apply cement only within the rudder area on the motor stick. Bend a paper clip and cement it to the motor stick as shown. On the front end put the prop unit in place. Assemble the model by slipping the wing saddle onto the motor stick and hold it in place with two small rubber bands. Get a loop of 1/4" flat rubber 18" long and connect it to the prop and rear hooks. Tie the rubber strand into a loop using a square knot.
Place the wing as indicated, and wind the propeller until the rubber has a single row of knots. Release the propeller and gently push the model forward. Observe the flight. If the model doesn't climb, slide the wing saddle forward. If it climbs up and then stalls, move the wing back. When a good climb and smooth glide are achieved, wind the propeller to two rows of knots and be ready for a good chase after the model.
After successfully building and flying this model, construct a second wing using 1/16 x 1/8" wood for the entire assembly. The wing is cemented where the first wing had been balanced on the motor stick. This will produce a lighter model, which will climb and glide much better. However, it is more liable to break and should be flown outdoors only when it is calm.
Thermal Dart Plans
Thermal Dart Plans (Black & White)
The AMA Plans Service offers a full-size
version of many of the plans show here at a very reasonable cost. They will scale the plans any size for you. It is always
best to buy printed plans because my scanner versions often have distortions that can cause parts to fit poorly. Purchasing
plans also help to support the operation of the Academy of Model
Aeronautics - the #1 advocate for model aviation throughout the world. If the AMA no longer has this plan on file, I
will be glad to send you my higher resolution version.
Try my Scale Calculator for Model Airplane Plans.
Posted June 29, 2013